The present invention relates to a workpiece handling apparatus.
Industrial robots are being introduced more and more into modern production technology. These robots can be, for example, workpiece handling apparatus which possess a workpiece gripper by means of which workpieces can be transported from a supply station/storage apparatus to a processing machine and vice versa and/or between processing machines. For this kind of workpiece handling apparatus and particularly for its workpiece gripper, it must be remembered that, on the one hand, the workpieces waiting to be transported may vary in shape and size. On the other, the apparatus must be capable of rotating individual workpieces so that the workpiece may be removed from the supply station in a position and direction other than the one in which it has to be surrendered to the processing machine and/or so that a workpiece can be machined from several sides by means of rotation of the workpiece during the process.
The search for as rational a production as is possible calls for the periods of inactivity of a processing machine to be kept to a minimum. It is advantageous then to provide more than one workpiece gripper in workpiece handling apparatus so that the already processed workpiece can be removed and carried away and, in the main, a workpiece waiting to be processed may be surrendered to this processing machine. A workpiece double gripper might, for example, be suitable for using here.
In order to be able to manipulate as wide a range of workpieces as possible with only one workpiece handling apparatus, it is advantageous to provide different workpiece grippers, adapted as required and to be able to substitute one for another. For example, it is recommended that there is provided workpiece grippers for chuck parts and ones for shafts. These may be inserted into the apparatus as required.
As previously stated, rotation of the workpiece and thereby of the workpiece gripper is an essential requirement of workpiece handling apparatus of this kind. The preferred angle of traverse of the workpiece gripper is 90.degree. spacing. Almost all manipulation tasks arising in connection with processing machines are fulfilled with this spacing.
The workpiece gripper unit has elements which can be moved towards each other, and by means of which it can grasp the workpiece, hold it firmly and then release it again. An adequate gripping force is needed for gripping and a counteracting force corresponding to that is needed for the release of the workpiece. These forces must be controllable in relation to each other in the workpiece gripper. The gripping power can be produced by the spring elements located inside the workpiece gripper. However, the action of a further, external force is necessary for the desired controllability. In the case of rotating, and only then, interchangeable workpiece grippers, the requirement that at least one other force should be transmissible in some way from outside onto the gripping elements of the workpiece gripper should be considered.
In a known workpiece handling apparatus disclosed in DE-OS No. 23 52 575, provision is made for a workpiece gripper and support arm which are both rotatable. The actuator for the gripping elements leads from behind, through the support arm to the gripping jaws. To power it, hydraulic elements are provided in the support arm which admit the hydraulic agent via a hosepipe in a controllable manner. Substitution of the workpiece gripper also calls for a substitution of the support arm as well and disconnection and recoupling of the hydraulic pipes.
Another known workpiece handling apparatus from "Maschine Werkzeug", Coburg, Special number October 1978, does indeed have a workpiece gripper which is rotatable towards the support arm of the apparatus. The actuator described is however, arranged on the gripper, and rotary transmission or flexible hose pipes are provided for putting energy into this actuator. Apart from the fact that the actuator on the workpiece gripper itself enlarges its scope and dimensions in an undesirable way, the devices needed for transmitting energy are sensitive and/or technically costly. A necessary substitution of the workpiece gripper would require disconnection and recoupling of this kind of transmission device.
An object of the present invention is to provide a workpiece handling apparatus whereby, despite rotatability of the workpiece gripper towards the support arm of the apparatus, a technically simple transmission of the controllable actuator of the gripping elements of the workpiece gripper onto this workpiece gripper is ensured. This transmission is done in such a way as to allow different workpiece grippers to be substituted for each other in straightforward manner.